Happy birthday King Juan Carlos: the monarch's life in pictures

In May 1962 Juan Carlos married Princess Sofia of Greece and Denmark, who would later become his Queen consort, in a stunning ceremony in Athens at the church of Saint Dennis.

During Juan Carlos and Sofia's honeymoon, the newlyweds travelled to the United States meeting President John F Kennedy and his wife Jackie Kennedy.

A year after their wedding, the couple welcomed their first daughter Infanta Elena, Duchess of Lugo and two years later, in 1965, Sofia gave birth to their second daughter Infanta Cristina, Duchess of Palma de Mallorca.

However, it would be in 1968 that the couple would welcome heir-apparent Felipe, Prince of Asturias, who is expected to become the king of Spain one day.

Similar to Britain's Princess Anne and Monaco's Prince Albert, Juan Carlos has taken part in the Olympic Games.

The sport-loving royal, pictured on sailing with his son Prince Felipe, was part of a sailing team that competed at the 1972 summer Olympics in Munich.

In November 1975 Juan Carlos was crowned the king of Spain after Spanish dictator Francisco Franco died, making him the first reigning monarch in Spain since 1931.

In 2000 the king celebrated his Silver Jubilee, celebrating 25 years on the throne.

Despite some recent troubles, King Juan Carlos has enjoyed public support and in 2008 he was named as the most popular leader in all Ibero-America, which covers all the areas in South America, Spain and Portugal that were once or are still colonies of Spain.

The adventurous monarch, who enjoys skiing, karate and motorcycle racing, is a member of the World Scout Foundation, which is headed by King Carl XVI Gustaf of Sweden (pictured).

The Scout organisation is also supported by the Duchess of Cambridge who volunteers when she has spare time.

The king is the great-great-grandson of Queen Victoria and is a distant cousin to both Queen Elizabeth II and Prince Philip.

In November 2013 the king left the Quiron University Hospital having undergone a successful hip replacement operation in September.

"Everything is very good. Fantastic. Thank you," he told reporters as he left, referring to his fifth operation in 18 months.

Juan Carlos was born on 5 January 1938 in Rome, Italy, to parents Infante Juan, Count of Barcelona (pictured) and Princess Maria Mercedes of Bourbon-Two Sicilies.

Upon birth the young royal was given the title of His Royal Highness The Infante Juan Carlos of Spain.